<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>glDrawBuffers - OpenGL ES 3.1 Reference Pages</title>
    <link rel="stylesheet" type="text/css" href="opengl-man.css"/>
    <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"/>
    <script type="text/x-mathjax-config">
            MathJax.Hub.Config({
                MathML: {
                    extensions: ["content-mathml.js"]
                },
                tex2jax: {
                    inlineMath: [['$','$'], ['\\(','\\)']]
                }
            });
        </script>
    <script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"/>
  </head>
  <body>
    <header/>
    <div class="refentry" id="glDrawBuffers">
      <div class="titlepage"/>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glDrawBuffers — Specifies a list of color buffers to be drawn into</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glDrawBuffers</strong>(</code>
              </td>
              <td>GLsizei <var class="pdparam">n</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>const GLenum *<var class="pdparam">bufs</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>n</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>Specifies the number of buffers in
            <em class="parameter"><code>bufs</code></em>.</p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>bufs</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>Points to an array of symbolic constants
            specifying the buffers into which fragment colors or
            data values will be written.</p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p><code class="function">glDrawBuffers</code> defines an array of
    buffers into which outputs from the fragment shader data will
    be written. If a fragment shader writes a value
    to one or more user defined output
    variables, then the value of each variable will be written into the
    buffer specified at a location within <em class="parameter"><code>bufs</code></em>
    corresponding to the location assigned to that user defined output.
    The draw buffer used for user defined outputs assigned to locations
    greater than or equal to <em class="parameter"><code>n</code></em> is implicitly set
    to <code class="constant">GL_NONE</code> and any data written to such an output
    is discarded.</p>
        <p>The symbolic constants contained in
    <em class="parameter"><code>bufs</code></em> must be one of the following, depending on
        whether GL is bound to the default framebuffer or not:</p>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <code class="constant">GL_NONE</code>
              </span>
            </dt>
            <dd>
              <p>The fragment shader output value is not written into
            any color buffer.</p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_BACK</code>
              </span>
            </dt>
            <dd>
              <p>The fragment shader output value is written into the
            back color buffer.</p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_COLOR_ATTACHMENT</code>
                <span class="emphasis">
                  <em>n</em>
                </span>
              </span>
            </dt>
            <dd>
              <p>The fragment shader output value is written into the
            <span class="emphasis"><em>n</em></span>th color attachment of the current framebuffer.
            <span class="emphasis"><em>n</em></span> may range from zero to the value of
            <code class="constant">GL_MAX_COLOR_ATTACHMENTS</code>.</p>
            </dd>
          </dl>
        </div>
        <p>Except for <code class="constant">GL_NONE</code>, the preceding
    symbolic constants may not appear more than once in
    <em class="parameter"><code>bufs</code></em>. The maximum number of draw buffers
    supported is implementation dependent and can be queried by
    calling
    <a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
    with the argument <code class="constant">GL_MAX_DRAW_BUFFERS</code>.</p>
      </div>
      <div class="refsect1" id="notes">
        <h2>Notes</h2>
        <p>If a fragment shader does not write to a user defined output variable,
    the values of the fragment
    colors following shader execution are undefined. For each
    fragment generated in this situation, a different value may be
    written into each of the buffers specified by
    <em class="parameter"><code>bufs</code></em>.</p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p><code class="constant">GL_INVALID_ENUM</code> is generated if one of the
    values in <em class="parameter"><code>bufs</code></em> is not an accepted
    value.</p>
        <p><code class="constant">GL_INVALID_OPERATION</code> is generated if the GL is bound
    to the default framebuffer and <em class="parameter"><code>n</code></em> is not 1, or if the value in
    <em class="parameter"><code>bufs</code></em> is one of the <code class="constant">GL_COLOR_ATTACHMENT</code><span class="emphasis"><em>n</em></span>
    tokens.</p>
        <p><code class="constant">GL_INVALID_OPERATION</code> is generated if the GL is bound
    to a framebuffer object and the ith buffer listed in <em class="parameter"><code>bufs</code></em>
    is anything other than <code class="constant">GL_NONE</code> or 
    <code class="constant">GL_COLOR_ATTACHMENTS</code><span class="emphasis"><em>i</em></span>.</p>
        <p><code class="constant">GL_INVALID_VALUE</code> is generated if
    <em class="parameter"><code>n</code></em> is less than 0 or greater than
    <code class="constant">GL_MAX_DRAW_BUFFERS</code>.</p>
      </div>
      <div class="refsect1" id="associatedgets">
        <h2>Associated Gets</h2>
        <p><a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
    with argument <code class="constant">GL_MAX_DRAW_BUFFERS</code></p>
        <p><a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
    with argument <code class="constant">GL_DRAW_BUFFER</code><span class="emphasis"><em>i</em></span> where
    <span class="emphasis"><em>i</em></span> indicates the number of the draw buffer
    whose value is to be queried.</p>
      </div>
      <div class="refsect1" id="versions">
        <h2>API Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">
                 
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="3">
                <span class="bold"><strong>OpenGL ES API Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">glDrawBuffers</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="glReadBuffer.xhtml"><span class="citerefentry"><span class="refentrytitle">glReadBuffer</span></span></a>
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright <span class="trademark"/>© 2003-2005 3Dlabs Inc. Ltd.
            Copyright <span class="trademark"/>© 2010-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p>
      </div>
    </div>
    <footer/>
  </body>
</html>
